k d a v t s



'Lata-s Patent-N0. 75,534, dammen 17,1868.

'IMPROVEMENT iii-'ADJUSTABLE srair-'ervnta itin tlnuar trattate iitilgtte Etnias ejiitent mit mating pitt ut tip: 5min.

-ro-A'LL WHOM Ir" MAY eoNoERN;

Be i-t known` that L. L. DAVIS,` of Springfield, in thecounty` ofi-Hampden, and Commonwealth of Massa' chnsett's, have invented a new and useful Improvement i'njAdjustable Spirit-Levels and-Ido lherebydeclare that 4the following is afull, clear, and exact description thereof, reference being had -to the acoompanyingdraw- V ings, making part'oi' Vthis specification, and to the letters oflreference marked thereon, inwhichf- Fignxfelzis aplan 'of a portion of 'a level with my invention applied.

`liigure 2`is a side elevationof the same, with a portion of the level cut away at 7c to more fullyshow the" construction and application of my invention to a level and i Figure' r3- is a planfiview of the bubble-glass case, with the bubble-glass inserted. ,p

The nature of my invention eonsis'tsin the construction andv rrangement ofa bubble-glass ease, whereby the-bubblelglass is much more readily y and perfectly adjusted with reference tothe stock than it is possible to do when constructed in theusual manner, and without any previous adjustment of the bubble-glass to its case when 'placed therein.' v

As now ,and usually constructed, the common spirit-levels of the cheaper quality are adjusted by. taking great care when inserting the bubble-glass in its ease to so insert itv and secure it in place that. the said bubblel' glass shall bein perfect and proper ,adjustment with its ease.` Y Such adjustment is ,only performed, attended with much difficulty and trouble, and oftentimes, with the greatest carve, the levels, when done, are not=in perfectadjustment, as there is no `way of changing theadjustmeut after the gypsum, with whichthe bubblelglass is 'secured in place, has set or become hard. y y

In my invention no care or exaetujess is required incthe insertion of the. bubble-glass in its case, as it is unnecessary that `the bubble-glass should be in 'adjustment with-dtsV case, as the -said bubble-glass isput in adjustment with the stock by means of the bubble-glass ease after-its vinsertion in the stock. I

That others skilled in' the art may be able toimak'e and use my invention, I will proceed to describe its construction and'application to use... y

'-In the'drawings, Arepresents .the stoekof a spirit-level., having a cavity, indicated by the dotted line c,

ag.v1,`mad'e therein, and of about the depth indicated by the line 7c k,.iig`.h 2, and also al still smaller cavity, o', for thereception of the projection o. vInto this 'largercavity c is inserted the bubble-glass ease'n-,having the bubble-glassy previously insertedrtherein, and Aproperlysecured by means of the gypsnn'i, or other proper sub-- ,l

stance, l. v t

The bubble-glass case 7L is constructed as follows: A'metallio' box 'is made of the proper size, having the sides '/j r and ends vr 7*', and having-ja bottom, but .no cover. To each end of the boxercase h are attached the l ears b" b', said ears being perforated near' their outer ends', and a screw-thread out in said perforation for' the reception of 'the screws f The upper edges r r of the case h are made crowning @slightly-convex, and a small semicireular spaee,-s,l is made-in each side of the ease7 so that the, bubble may beiseenbeneath the plate a, rIfhe -ear or projection ois'rmly attached to the-bottom of the'case h, said projection o lbeing perforated.

i at n, through which a small pin or-pivotis passed, which alsofpasses through Athe` stock' A, thus'securingl the ease It to thev stockA at'the pointn. A small space should beleft between the bottom c of the'cavity c and the ease h, to allow each end of s'aidcase t a slight verticalplay whenever `its position shall be'changed byl turningthe screws ff either in or out. Thepiate a is 'then placed above the case t, andattached to the stock A by meansofthe screws e e ee, it being better to lslightly. cut away the upper -su'rfaceof 'the stock A and let theplate aimso that4 the 'uppergsurface of the said plate a shallfbe upon the same level with the upper surface of thestock Arandthe screws are inserted-in aperturesmade-in the plate a, one near each end, and

-turned orseewed'into lthe`threaded apertures in each ear i of the case h. Thesefears' z' beingfattaehed to the lower part of ,eachl end-off 'thezease h, and behtupwards, are thus renderedl elastic, 'so that when the bubbleglass is lin adjustment with the stock A,'ahd the screws f f vare turned up firmly, the bubble-glass or its case shall alw'ays ,hear up 'against theplate arend the dass is thus rmly'held in place, and prevented from shall-` 4ing'in its socket, and rendering the bubble-g`lass less `liable to breakage.

This arrangement, I claim, has a great advantageoverother 'adjustable'.,levelsfas now constructed.

The operation of my invention isasfollows: If upon trial the bubble-glass shall be found to be out oi'- its proper adjustment with reference to the stock A, one of the screws f is turned farther into one ot" the ears z'. As the head of lthe `screw 7" comes in contact with the upper surface ofethe plate a, the ear t', into which the screw f is turned, is drawn upward, and the middle-of the case lz', stvinging upon its pivot n, the othenscrew f being turned out, its end of tho said ease 71. lis depressed. In this way either end of the case h may be raised or depressed, until the bubble-case g shall be 'found to be in proper adjustment with the stock A, or the axis of the bubble-glass g shall be exactly parallel with the bottom of tbe stockA. Both ears 'i a' are pre'vcnted from coming in Contact with the under surface of the plate aat the same time by the convex form of the upper edges `r r of the box or easeL, and also by the pin n. l

Spirit-levels have heretofore been made in which the bubble-glass case was adjustable, but, as said case was not positively and properly secured in its stock after adjustment, they are liable to quickly get out of adjustment again, as, if'the stock be turned upside down, the case moves in its socket, and renders the bubble or vial liable to r'be broken or misplaced in its case; and I am aware that various devices have been used for the purpose of rendering spirit-levelsadjustable after their first construction as in Letters Patent granted to T. N. Hosmer, bearing date November`11, 1862, and numbered 39,906, and others, but'said'dev'ices differ very materialy from mine in construction,arrangetnent, and operation, and Ldisclaim any andA every part of said devices irrespective of my arrangement and construction; but having described my invention,

What I do claim as new, and desire to secure by Letters Patent, is,

11. The adjustable bubble-glass `case "h, having the elastic adjusting-ears 'L'zand projection o, when-constructed and arranged substantially' as described andfor the purposes hereinset forth.

2. I claim, in an adjustable spirit-level, the case k having the elasticadjusting-ears z'z'and the projection o,

and operated or adjusted by means of the'screwsff, in combination with the plate a and pin n, substantially as herein described and set forth.

. L.L. DAVIS.

Witnesses:

J. 13. BUcKLND, N. B. SMITH. 

